Sierra 18-3319

Upgrade Your Outboard's Cooling System with Confidence

Keeping your boat's engine running cool under pressure is essential for every trip on the water. The Sierra 18-3319 engine parts kit steps in as a reliable solution for maintaining optimal water pump performance in popular Mercury and Mariner outboards. Designed to match the exact specifications of OEM components like the 46-96148A8 and 46-42579A3 equivalents, this kit delivers the durability and flow you need without compromising on quality.

What sets this apart? It's built with precision-engineered materials that resist wear from constant exposure to saltwater, sand, and debris. Boaters who swap in this kit often notice smoother operation and fewer overheating issues, extending the life of their lower unit and saving on costly repairs down the line.

Perfect Fit for High-Performance 4-Stroke Engines

This kit is tailored for a wide range of Mercury 4-stroke outboards, particularly those in the 4- and 6-cylinder families from 75 HP up to 300 HP. It slots right into models that demand a robust water pump base and impeller setup, ensuring seamless water circulation during high-RPM runs or long cruises.

• Compatible with key Mercury Verado, FourStroke, and OptiMax series
• Ideal for both freshwater and saltwater environments
• Direct replacement for factory wear items

What's Inside the Kit: Everything You Need for a Quick Rebuild

Unlike basic impeller-only replacements, the Sierra 18-3319 provides a complete overhaul package. You'll get the pump base, impeller, wear plate, and necessary seals and gaskets—all pre-matched for hassle-free assembly. This all-in-one approach means less time sourcing parts and more time on the water.

Step-by-Step Installation Tips for DIY Boaters

Installing this kit is straightforward with basic tools, but attention to detail prevents leaks or imbalances. Start by flushing the system and draining the lower unit gear oil. Remove the old pump housing, clean mating surfaces thoroughly, and inspect for gear wear. Lubricate the new impeller with marine grease, align the keyway precisely, and torque bolts to spec (typically 80-100 in-lbs). A final water test on muffs confirms flow before hitting the lake.

Why Boaters Trust Sierra Over Stock Parts

Sierra has earned its stripes in the marine world by offering OEM-level performance at a fraction of dealer costs. Each kit undergoes rigorous testing for impeller spin-up speed and flow rates, mimicking factory standards. Real-world feedback from salt-water warriors highlights fewer failures compared to generics, making it a smart pick for weekend warriors and pros alike.